/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 * <p>
 * http://www.apache.org/licenses/LICENSE-2.0
 * <p>
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */

package org.apache.iotdb.tsfile.file.metadata;

import org.apache.iotdb.tsfile.common.conf.TSFileDescriptor;
import org.apache.iotdb.tsfile.read.common.Path;
import org.apache.iotdb.tsfile.utils.BloomFilter;
import org.apache.iotdb.tsfile.utils.ReadWriteForEncodingUtils;
import org.apache.iotdb.tsfile.utils.ReadWriteIOUtils;

import java.io.IOException;
import java.io.OutputStream;
import java.nio.ByteBuffer;
import java.util.Set;

/**
 * TSFileMetaData collects all metadata info and saves in its data structure.
 */
public class TsFileMetadata {

    // bloom filter
    private BloomFilter bloomFilter;

    // List of <name, offset, childMetadataIndexType>
    private MetadataIndexNode metadataIndex;

    // offset of MetaMarker.SEPARATOR
    private long metaOffset;

    /**
     * deserialize data from the buffer.
     *
     * @param buffer -buffer use to deserialize
     * @return -a instance of TsFileMetaData
     */
    public static TsFileMetadata deserializeFrom(ByteBuffer buffer) {
        TsFileMetadata fileMetaData = new TsFileMetadata();

        // metadataIndex
        fileMetaData.metadataIndex = MetadataIndexNode.deserializeFrom(buffer);

        // metaOffset
        long metaOffset = ReadWriteIOUtils.readLong(buffer);
        fileMetaData.setMetaOffset(metaOffset);

        // read bloom filter
        if (buffer.hasRemaining()) {
            byte[] bytes = ReadWriteIOUtils.readByteBufferWithSelfDescriptionLength(buffer);
            int filterSize = ReadWriteForEncodingUtils.readUnsignedVarInt(buffer);
            int hashFunctionSize = ReadWriteForEncodingUtils.readUnsignedVarInt(buffer);
            fileMetaData.bloomFilter = BloomFilter.buildBloomFilter(bytes, filterSize, hashFunctionSize);
        }

        return fileMetaData;
    }

    public BloomFilter getBloomFilter() {
        return bloomFilter;
    }

    public void setBloomFilter(BloomFilter bloomFilter) {
        this.bloomFilter = bloomFilter;
    }

    /**
     * use the given outputStream to serialize.
     *
     * @param outputStream -output stream to determine byte length
     * @return -byte length
     */
    public int serializeTo(OutputStream outputStream) throws IOException {
        int byteLen = 0;

        // metadataIndex
        if (metadataIndex != null) {
            byteLen += metadataIndex.serializeTo(outputStream);
        } else {
            byteLen += ReadWriteIOUtils.write(0, outputStream);
        }

        // metaOffset
        byteLen += ReadWriteIOUtils.write(metaOffset, outputStream);

        return byteLen;
    }

    /**
     * use the given outputStream to serialize bloom filter.
     *
     * @param outputStream -output stream to determine byte length
     * @return -byte length
     */
    public int buildAndSerializeBloomFilter(OutputStream outputStream, Set<Path> paths)
            throws IOException {
        BloomFilter filter = buildBloomFilter(paths);
        return serializeBloomFilter(outputStream, filter);
    }

    public int serializeBloomFilter(OutputStream outputStream, BloomFilter filter)
            throws IOException {
        int byteLen = 0;
        byte[] bytes = filter.serialize();
        byteLen += ReadWriteForEncodingUtils.writeUnsignedVarInt(bytes.length, outputStream);
        outputStream.write(bytes);
        byteLen += bytes.length;
        byteLen += ReadWriteForEncodingUtils.writeUnsignedVarInt(filter.getSize(), outputStream);
        byteLen +=
                ReadWriteForEncodingUtils.writeUnsignedVarInt(filter.getHashFunctionSize(), outputStream);
        return byteLen;
    }

    /**
     * build bloom filter
     *
     * @return bloom filter
     */
    private BloomFilter buildBloomFilter(Set<Path> paths) {
        BloomFilter filter =
                BloomFilter.getEmptyBloomFilter(
                        TSFileDescriptor.getInstance().getConfig().getBloomFilterErrorRate(), paths.size());
        for (Path path : paths) {
            filter.add(path.toString());
        }
        return filter;
    }

    public long getMetaOffset() {
        return metaOffset;
    }

    public void setMetaOffset(long metaOffset) {
        this.metaOffset = metaOffset;
    }

    public MetadataIndexNode getMetadataIndex() {
        return metadataIndex;
    }

    public void setMetadataIndex(MetadataIndexNode metadataIndex) {
        this.metadataIndex = metadataIndex;
    }
}
